Current videophones use cameras having a long depth of field which results in the subject matter in a scene captured by the camera from foreground to background being in focus. This compares to video images captured by cameras having a shorter depth of field where subject matter in the foreground appears in focus while subject matter in the background of the scene appears out of focus.
Long depth of field in videophones generally results from a small digital imaging sensor size relative to the lens aperture in combination with a fixed focal length and shutter speed. These particular design parameters are selected in order to provide good videophone image quality while maintaining low component costs which is important for videophones sold into the highly competitive consumer electronics market.
Consumer-market videophones provide excellent performance overall, and the long depth of field provided is normally acceptable in many settings. Not only does it provide a perception that the videophone image is sharp and clear overall, but a videophone can be used in a variety of settings without the user worrying that some portions of a captured scene be out of focus. For example, a group of people on one end of a videophone call can have some participants positioned close to the camera while others are farther away. Another user may wish to use the videophone to show something that needs to be kept at some distance from the camera.
However, the videophone's long depth of field can present issues in some situations. Some users may find the details in the background of the received video image to be distracting. Others might be uncomfortable that their videophone captures too a clear view of themselves, their home, or surroundings and represents some degree of intrusion on their privacy. And even for those users who fully embrace the videophone's capabilities, it is possible that details of a user's life may be unintendedly revealed during a videophone call. For example, a person might not realize that a videophone call is taking place and walk through the background in a state of attire that is inappropriate for viewing by people outside the home.
One current solution to address privacy concerns includes placing controls on the videophone that let a user turn the videophone camera off while keeping the audio portion of the call intact. While effective in many situations, it represents an all or none solution that not all users accept since the loss of the video function removes a primary feature provided by the videophone. In addition, such user controls do not prevent the accidental capture of undesirable or inappropriate content by the videophone.